>> I found the best tool to be a loud music source.  Masks all the little
sounds you think are the van falling apart. <<

Exactly the reason I have never upgraded my 1980's vintage stereo/cassette deck in my Westy. I NEVER listen to the radio so loud as to drown out engine noise, I have to hear that engine and any strange noises that pop up. I had a '77 Bay Westy years ago that I gutted to do a complete color change repaint on. On reassembling the interior, I filled the ribs with foam, and sprayed the entire inside with 3M rubberized undercoating, then added sound proofing. The result was the quietest Bay I've ever seen-I hated it! The ride was quiet, but I could barely hear the engine running, and that made me feel uncomfortable. I'd rather hear little noises before they become big problems!   Jeff